The capture of high-energy images of a given object using penetrating energy (such as X-rays or the like) is well known in the art. Such high-energy images often comprise images having areas that are relatively darker or lighter (or which otherwise contrast with respect to one another) as a function of the density, path length, and/or composition of the constituent materials that comprise the scene being imaged. This, in turn, can serve to provide views of objects that are otherwise obfuscated from visual inspection.
The use of high-energy images finds myriad applications. For example, in a security application setting such images can help to provide views of objects that are illegal and/or that pose a potential threat. Prior art approaches also disclose ways to leverage high-energy images in order to determine the material composition of such objects.
Unfortunately, however, corresponding needs in these regards are logistically daunting. While the need to examine untold numbers of shipping containers at ports of entry is very real, for example, the sheer volume of content to be examined renders essentially all prior art approaches outmatched. This includes prior art approaches that automate to some significant degree the image-capture and/or image-analysis process.
Additionally, since X-ray imaging tends to superimpose objects in a radiographic image, existing methods to determine material composition of superimposed objects in general can typically only determine the composition of the superimposed combination. Often, however, to make an accurate risk assessment, it is preferable to determine a separate material composition for each superimposed object. While superposition is generally not a problem in three-dimensional imaging methods such as computerized tomography (CT), the ability to separately identify the composition of superimposed materials has been lacking in existing two-dimensional imaging approaches.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.